The present invention relates to a cable tray for electric cable used in buildings, factories and other structures and particularly to a seismic brace or restraint for the cable tray.
Electric wire or cables extend through homes, factories, buildings and other structures. The cables could be stretched the substantial distance between widely spaced supports. But they would hang down, stretch or be damaged. The cables are instead supported on elongate trays that are suspended from ceilings, beams, walls, etc. along their path to where the cables are connected.
Cable trays can take various forms. One type, for which the invention is particularly adapted, is suspended from an overhead structure, such as a ceiling, the underside of the floor above, structural beams, etc. This cable tray may have an elongate center support or spine with elongate trays extending along opposite sides of the center support spine, or possibly may have an "L" arrangement with a vertical support and a cable supporting tray off to only one lateral side of the support. The cable tray is supported from the structure above by hangers located at spaced apart intervals along the tray.
Some geographic localities are subject to earthquakes and earth tremors. Building code writers and builders have desired a seismic restraint or brace for supporting a cable tray, which restraint or brace can be subjected to the movement of a structure during an earth tremor without the brace breaking or releasing its hold on the cable tray or separating from the supporting structure above.
A cable tray is assembled from a plurality of elongate sections. Each of the sections may have a central spine. The ends of adjacent sections meet at a splice connector. Normally, a simple cable tray hanger rod is attached between the splice connector and the supporting structure above the hanger rod. In the event of an earth tremor or earthquake, the hanger rod may separate from the support above it, or may break the rod, or connector or spine, or the splice connector may separate from the hanger rod or from the spine of one of the sections of the cable tray.